The present invention relates to environmental control systems for aircraft and, more particularly, to a modular air conditioning unit for supplying temperature-controlled air to an aircraft environmental control system during ground support operations.
Aircraft main engines not only provide propulsion for the aircraft, but in many instances may also be used to drive various other rotating components such as, for example, generators and pumps. The main engines may also be used to supply compressed air to the aircraft""s environmental control system, which may be used to supply temperature-controlled air to both the aircraft cabin and to electronic equipment within the aircraft.
When an aircraft is on the ground and its main engines are not being used, an alternative power source may be used to supply power for ground support operations. In addition, during some ground support operations, an external supply of cooling and heating air may be used to supply temperature-controlled air to the cabin and aircraft equipment. For some type of aircraft ground support applications, most notably military aircraft ground support applications, a ground cart may be used to supply electrical power to the aircraft and compressed air to an air conditioning system module. The air conditioning module in turn may supply temperature-controlled air to the aircraft cabin and the aircraft""s electronic equipment.
One particular air conditioning system module that may be used during aircraft ground support operations receives compressed air supplied by the ground cart, and conditions the compressed air to a predetermined temperature. The air conditioning system module may be used in either a cooling mode, to supply cool air, or in a heating mode, to supply warm air. To do so, the air conditioning system module may include a primary heat exchanger, a condenser, a moisture separator, and one or more cooling turbines. Typically, when the air conditioning system module is being used in the heating mode, all of the components within the system, including the cooling turbines, are operating. The air exhausted from the cooling turbines is relatively cold (e.g.,  less than 55 F.). Hence, to supply warm air to the aircraft at the desired temperature (e.g., 55-200 F.), a portion of the relatively hot (e.g.,  greater than 300 F.) compressed air that is supplied to the air conditioning system module is diverted into cold air stream exhausted from the cooling turbines.
Although the above-described system and method for supplying warm air to an aircraft during ground support operations is effective, it suffers certain drawbacks. For example, because the cooling turbines are run in both the heating and cooling modes, the cooling turbines have relatively high operating hours, which can potentially reduce their operating lifetimes. Moreover, the operation of the cooling turbines in the heating mode is relatively inefficient, since the cooling turbines are used to cool the air and then this cooled air is subsequently warmed up.
Hence, there is a need for a system and method of providing temperature-controlled air to an aircraft environmental control system during ground support operations that does not use cooling turbines during a heating mode and/or is more efficient during than heat mode than presently known systems and methods. The present invention addresses one or more of these needs.
The present invention provides a system and method of supplying temperature-controlled air to an aircraft environmental control system during ground support operations that is simple, efficient, and does not adversely affect component lifetimes within the system.
In one embodiment of the present invention, and by way of example only, a temperature-controlled air supply system for use with a compressed air source and for connection to an aircraft on the ground includes an air amplifier, a first heat exchanger, a pressure control passage and a first valve. The air amplifier has at least a cooling air inlet port, a cooling air outlet port, an interior passageway therebetween, and a control air inlet port leading to the passageway. The first heat exchanger assembly is adapted to receive a flow of compressed air from the compressed air source and a flow of cooling air and to transfer heat from the compressed air to the cooling air and supply cooled compressed air. The pressure control passage has an inlet and an outlet, the inlet is configured to receive compressed air flow and the outlet is in fluid communication with the air amplifier control port. The first valve is mounted on the control pressure passage and is selectively moveable to control compressed air flow rate and pressure to the air amplifier control air inlet port.
In another exemplary embodiment, a method of supplying temperature-controlled air to at least one section of an aircraft during ground support operations includes flowing compressed air through a heat exchanger, and cooling air through an air amplifier and the heat exchanger to thereby cool the compressed air to a predetermined temperature. A flow of a portion of the compressed air to a control port of the air amplifier is controlled to thereby control the flow of the cooling air through the heat exchanger, whereby the predetermined temperature of the cooled compressed air is controlled.
Other independent features and advantages of the preferred air conditioning system will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.